991242621 has 24 divisors (see below), whose sum is σ = 1447875000. Its totient is φ = 653432832.

The previous prime is 991242601. The next prime is 991242641. The reversal of 991242621 is 126242199.

991242621 is a `hidden beast` number, since 9 + 9 + 1 + 24 + 2 + 621 = 666.

It is an interprime number because it is at equal distance from previous prime (991242601) and next prime (991242641).

It can be written as a sum of positive squares in 4 ways, for example, as 376748100 + 614494521 = 19410^2 + 24789^2 .

It is not a de Polignac number, because 991242621 - 2⁵ = 991242589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991242601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 793005 + ... + 794253.

It is an arithmetic number, because the mean of its divisors is an integer number (60328125).

Almost surely, 2^991242621 is an apocalyptic number.

It is an amenable number.

991242621 is a deficient number, since it is larger than the sum of its proper divisors (456632379).

991242621 is a wasteful number, since it uses less digits than its factorization.

991242621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2173 (or 2170 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 991242621 is about 31484.0057965946. The cubic root of 991242621 is about 997.0723106666.

The spelling of 991242621 in words is "nine hundred ninety-one million, two hundred forty-two thousand, six hundred twenty-one".